Chemical reaction engineering – characteristics of a zero-order reaction For a zero-order chemical reaction, which of the following statements are true?

Introduction / Context:
Zero-order reactions are an important special case in chemical reaction engineering where the rate is independent of reactant concentration. Such behavior is often observed in catalytic systems at saturation, photochemical reactions, or enzyme kinetics at very high substrate levels. Understanding time–concentration profiles and half-life scaling helps with reactor sizing and conversion prediction.

Given Data / Assumptions:

• Overall rate law: r = k (constant), independent of concentration.
• Isothermal, well-mixed (batch) conditions for interpreting time profiles.
• Products start at zero concentration unless otherwise stated.

Concept / Approach:
For a zero-order reaction consuming A to form products P, the material balance in a batch reactor is dC_A/dt = −k, which integrates to C_A = C_A0 − k t. Product concentration C_P then grows as k t (assuming stoichiometric 1:1), a linear relation with time. The half-life t_1/2 is the time required for C_A to drop to C_A0/2, which gives t_1/2 = C_A0/(2k); it scales directly with the initial concentration C_A0.

Step-by-Step Solution:

Verification / Alternative check:
Dimensional check confirms k has units of concentration/time for zero order; linear changes in both reactant consumption and product formation with time are consistent with constant rate.

Why Other Options Are Wrong:

• Options (a), (b), and (c) are each true individually; the most complete correct choice is “All (a), (b) and (c)”.

Common Pitfalls:
Confusing zero-order with first-order kinetics; first order shows exponential decay and constant half-life independent of initial concentration, which is not the case here.

Final Answer:
All (a), (b) and (c).